1Environment Canada, Downsview, Ontario, Canada
2Atmospheric and Environmental Research, Inc., Lexington, Massachusetts, USA
3Jet Propulsion Laboratory, California Institute of Technology Pasadena, CA, USA
4University of Colorado, Boulder, Colorado, USA
5US Environmental Protection Agency, Research Triangle Park, North Carolina, USA
6Spectroscopie de l'Atmosphere, Service de Chimie Quantique et Photophysique, Universite Libre de Bruxelles (U.L.B.), Brussels, Belguim
*presently at: Atmospheric and Climate Applications (ACApps), Inc., East Gwillimbury, Ontario, Canada
**formerly at: NASA Langley Research Center, Hampton, VA, USA
Received: 08 Mar 2011 – Discussion started: 26 May 2011
Abstract. Presently only limited sets of tropospheric ammonia (NH3) measurements in the Earth's atmosphere have been reported from satellite and surface station measurements, despite the well-documented negative impact of NH3 on the environment and human health. Presented here is a detailed description of the satellite retrieval strategy and analysis for the Tropospheric Emission Spectrometer (TES) using simulations and measurements. These results show that: (i) the level of detectability for a representative boundary layer TES NH3 mixing ratio value is ~0.4 ppbv, which typically corresponds to a profile that contains a maximum level value of ~1 ppbv; (ii) TES NH3 retrievals generally provide at most one degree of freedom for signal (DOFS), with peak sensitivity between 700 and 900 mbar; (iii) TES NH3 retrievals show significant spatial and seasonal variability of NH3 globally; (iv) initial comparisons of TES observations with GEOS-CHEM estimates show TES values being higher overall. Important differences and similarities between modeled and observed seasonal and spatial trends are noted, with discrepancies indicating areas where the timing and magnitude of modeled NH3 emissions from agricultural sources, and to lesser extent biomass burning sources, need further study.
Revised: 06 Oct 2011 – Accepted: 07 Oct 2011 – Published: 31 Oct 2011
Shephard, M. W., Cady-Pereira, K. E., Luo, M., Henze, D. K., Pinder, R. W., Walker, J. T., Rinsland, C. P., Bash, J. O., Zhu, L., Payne, V. H., and Clarisse, L.: TES ammonia retrieval strategy and global observations of the spatial and seasonal variability of ammonia, Atmos. Chem. Phys., 11, 10743-10763, doi:10.5194/acp-11-10743-2011, 2011.